High-frequency electrical apparatus



Feb. 19, 1957 Filed Oct. 16, 1952 J. E. G. COSIER ET AL HIGH-FREQUENCY ELECTRICAL APPARATUS 2 Sheets-Sheet 1 IN VEN TOR ROBERT JOHN CAVE JOHN EDWARD GEORGE COSIER AGENT Feb. 19, 1957 J. E. G. COSIER ET AL 2,782,281

HIGH-FREQUENCY ELECTRICAL APPARATUS Filed Oct. 16, 1952 2 Sheets-Sheet 2 ca c: c5 -c5 hi I v T rm I X I l I IN VENTOR ROBERT JOHN CAVE JOHN EDWARD GEORGE COSIER AGENT 2,782,281 HIGH-FREQUENCY ELECTRICAL APPARATUS John Edward George Cosier, Purley, and Robert John Cave, Caterham, England, assignors to Hartford National Bank and Trust Company, Hartford, Conn, as trustee Application October 16, 1952, Serial No. 315,092

Claims priority, application Great Britain December 20, 1951 Claims. (Cl. 200-98) This invention relates to high-frequency electrical apparatus and has for its object to provide a high-frequency electrical switch to enable one high-frequency electrical generator to serve two or more Working positions.

One position, e. g. a H. F. induction heating device, may be supplied with high-frequency electrical energy while another or others are being unloaded and loaded and thus economy is possible in that the high-frequency electrical generator is operable for a greater time per day. Normally, generator time is lost while unloading and loading is carried out at the single working position.

The invention also relates to a circuit-arrangement comprising a high-frequency generator and a high-frequency switch.

According to the invention, a switch for high-frequency currents comprises a set of movable contacts, a switch member electrically connected to said movable contacts, said contacts being alternatively conected to one of at least two sets of fixed contacts, characterised in that said movable switch member comprises a hollow conductive bellows electrically connecting the switch member to said movable contacts and permitting movement of movable switch member. The thickness of the conductive material forming the bellows is preferably between five thousandths of an inch and eight thousandths of an inch.

The movable switch member may comprise two arms each having a rigid top part supplied in an insulating manner connected thereto by way of the bellows a hollow tube part flattened at the lower end and two contacts secured one on each side of the flattened portion of the hollow tube part.

The switch may comprise two fixed contacts for conducting high-frequency energy to the first operating position, two movable contacts for providing connection to said fixed contacts and each secured to a different arm, two further fixed contacts for conducting high-frequency energy to the second operating position and two further movable contacts for providing connection to said further fixed contacts and secured one to each of the two arms.

The fixed contacts may be four copper blocks and the associated movable contacts may be laminated and made from beryllium-copper plates.

A flow path may be provided for coolant liquid by way of the rigid top part, the bellows and the hollow tube part of one arm, a connecting means and the hollow United States Patent tube part, the bellows and the rigid top part of the other face of the associated fixed contact in the operated posiice tion of the movable contact such that the contact surface of the fixed contact is adapted to be scraped by the laminations as contact between the movable and fixed contacts is being made.

Preferably two toggle mechanisms are provided each controlled by a solenoid screened electrically from the high-frequency part of the switch.

The switch preferably comprises a metal frame having two armature members suspended from and insulated from the central upper part of the frame, two solenoids secured one at each side of the upper part of the frame, a toggle mechanism associated with each solenoid and secured to and insulated from the armature members, and four fixed contacts two at each side of the lower part of the frame secured to and insulated from the frame.

The invention also relates to a circuit for high-frequency heating comprising such a high-frequency elecrical switch.

In order that the invention may be more clearly understood and more readily carried into effect, it will now be described more fully with reference to the accompanying diagrammatic drawings given, by way of example, in which:

Fig. 1 is a side-view of a switch according to the invention and Fig. 2 is a circuit-arrangement comprising a switch according to the invention.

Referring now to Fig. 1, the switch comprises an aluminium frame 1 supporting two pairs of fixed copper contacts 2, two movable switch members 3 and two solenoids 4.

The means 3 each comprises means to receive highfrequency electrical energy, in this case a threaded union 5 of copper, which is soft soldered to one end of a brass bellows 6 having a wall thickness of about seven thousandths of an inch. The other end of the bellows 6 is soft soldered to a copper tube 7 having a fiat portion 8 which in section has flat sides and rounded ends. The lower end of the tube 7 is silver-so1dered into an aperture in the wall of a tube 9 having a right-angled bend and being closed at on end and at its other, lower end secured to a union it).

Each means 3 also comprises two contacts 15 of laminated beryllium-copper secured each between copper strips 15 one on each flat surface of the portion 8 by bolts each passing through the laminations of both contacts 15 and through the portion 8. The lower surfaces of the contacts 15 constitute contact surfaces and are machined at an angle of about 45 to the longitudinal directions of the laminations.

Each means 3 is supported from a block 11 of insulating bakelised plywood secured between two transverse strips 12 of bakelised plywood which in turn are bolted to lugs 13 secured to upstanding portions 14 of the frame 1.

The two means 3 of which only one is visible in Fig. 1, the second being directly behind that shown, are each water-tight and each in operation of the switch, will be cooled, for example, by a current of water supplied through one union 5 and passing through the associated bellows 6, tube 7, tube 9 and union 10, to a flexible insulation tube, such as rubber tube, secured to one union it at its one end and to the other union 1%) at its other end. The water then fiows upwards through the other means 3 and out of the associated other union 5. Alternatively a separate flow of cooling fluid may be provided for each means 3.

Each of the four copper contacts 2 is secured to the frame 1 with the interposition of a ceramic insulator 16,

the contact face 17 of each contact 2 being at an angle 4 to co-operate satisfactorily, i. e. to provide a good contact with, the associated contact 15, the contacts 2 being arranged one to each side of each means 3. Through each contact 2 passes a U-shaped copper tube 19 constituting;means to conduct high frequency; energy. to anE operating, position. Thecontacts Zara-cooled,-v for. ex, ample, by a current of waterpassingthrought one end of one tube 19, through a flexible insulating tube and throughthe other tube 19 on theright-hand side of the switch and by a current, of water passing inanexactly similar manner on the left-handside of theswitch. Each contactface 17' has securedto itabove the associated contact 2 a conductive lug 18.

The solenoids 4-are provided near the-top-and, one

at each side of the switch. The armature 19a of each of bolts passing also throughspacers 26 of bakelised ply wood so shaped and arranged that. the desired relationships of toggle mechanisms and contacts is obtained.

The, two solenoids 4 are. each shielded from the rest of the switch by means of an aluminum screen, 27, provided witha slit for passage. and movement of thearm 20. A projection 28 is provided on eachtogglemechanism adapted, to co-operate each withoneof the lugs 18 to provide safety grounding of that outlet of. the operated switch not inuse.

The switch is shown operated in Fig. 1, the leftshand contacts} being in contact with the, left-hand contacts 15 due to energization of, the right-hand relay 4 and consequent straightening of the left-hand toggle mechanism to within about 3 of the full 180. When the relay is operated the contact 15 scrapes against the associated contact 2 to provide a good and clean high-frequency connection.

The switch is designed to operate on no-load, the highfrequency generator being switched-off when the switch is changed from, its normal position, that is, its position in which neither solenoid 4 is energized and consequently the switch member 3 hangs vertically downwards, to an operated position or from one operated position to the other. The high-frequency generator is thereafter switched on.

Referring now to Fig. 2, the circuit arrangement comprises two solenoids A and B, each associated with a solenoid (auxiliary) winding a and b, respectively. The solenoids A and B are the solenoids 4. of Fig. 1. The auxiliary windings a and b each supply an indicator lamp La and Lb respectively. A relay Ra is connected in parallel with the solenoid Aand a relay Rb is connected in parallel with the solenoid B; One end of each of thesolenoids A and B and of the relays Ra and Rb is connected to a conductor C1. The other end of the solenoid A and the relay Ra are connected to contact PaL of a push button Pa, the contact Pa2 of which is connected to a conductor C2. The said other ends of the solenoid A and relay Ra are also connected to the conductor C2 by way of. its own holding contact ral (normally open) and the parallel connection of a contact rb2 (normallyclosed) of relay Rb and a contact-hi1 of a high tensioninterlock relayHt. Solenoid B and relay Rb are similarly connected with the use of push button Plrhaving contacts Pbl and PM and contacts rbl, m2 and M2;

A second circuit is formed from a conductor C3, contacts' Pa3'and'. P6141 of push-button Pa, contacts PM and Pb'dof. push-buttonPb and conductor- C4. The conductorsC3 and-C4 complete a circuitto a relay (not shown) controllingthe electrical supply-to and in thehigh-fre 4 quency generator. Contacts Pa3 and Pa4 and contacts PBS and PM are normally bridged.

A third circuit is formed from conductor C1 through relay I-IT to a conductor C5. Relay HT is energised only if the high tension voltage is switched on in the high-frequency generator.

The operation of the circuit arrangement is. as follows:

(a It the high tension voltage is switched off in the high-frequency generator and the button Pa is pressed, solenoid A and relay Ra energise. Lamp La is supplied with current from auxiliary winding a inductively coupled withsolenoid. A. Contact m1 closes and contact m2 opens, cont act m1 completing a holding circuit for relay Ra when the button Pa. is released. Operation of the solenoid A causes the means 3 to prepare a highfrequency path to thecontacts 2 on-the opposite side of the high-frequency switch. High tension supply can then beswitch on for, the high-frequency generator causing relay HT to energise and close contacts hi1 and ht2.

lf now. button Pb is pressed, current is supplied to relay Rb whichenergi ses together, with solenoid B. The

operation of; button Pb however, opens the circuit from conductor; C3 to conductor C4 at contacts Pb3 and PM and the; relay- (not shown) inthe high-frequency generator cuts; off the high tension supply to the generator. Relay HT. then de-energises and contacts htl and M2 open. The high frequency switch cannot switchover until relay, HT de-energises even though both solenoids A and B, areenergised, since solenoid B is operating at a mechanical. disadvantage through the associated arms 20 and 21 compared with solenoid A.

Whenboth relays Ra and Rb are energised and relay HT is subsequently de-energised, contacts m2 and-rbZ; are. open, and the subsequent opening of 'contactshtl and ht2,break s the connections for relays Ru and Rb and for solenoids A. and B to the conductor C2 so that if buttonPb isat this time rel-eased both relays Rwand,

Rb-and both solenoids A and B de-energise. In practice, therelay. HT de-energises quickly and the switch ply to the generator toprevent the high-tension being switched on if jthe switch member 3 is in its central-position. The interlockcontactsmay becontrolled by the provision of further contacts (not shown) for relays Ra and Rb- The solenoids A and B are supplied throughthegenerator power supply so that a supply fault will be common to the generator and the solenoids A and B, that is, if the solenoid supply is so cut off the high tension supply to the generator will also be cut off.

Extension controls may be provided at the operating positions, for example, by providing suitable extension relays and-push buttons connected to the circuit described with reference to Fig. 2 by conductors shown in broken lines.

If it is desired to provide that in the event of failure of one of the solenoids, for example, due to a fault in the solenoid winding, that the switch remains in its operated position, the switch may be modified such that {the toggle mechanisms 20 and 21 pass beyond the straight positions when operated. In this case, it will be necessary to provide two additional solenoids for unlocking, that is forcing the operated toggle mechanisms Ztland 21 through its straight position, on change-over of the switch member 3;

What we claim is:

1. A switch for high-frequency currents comprising a plurality of fixed first contacts, a movable switch member being provided with a plurality of second contacts each of which may be alternately connected to one of said fixed first contacts, said switch member including a hollow conductive bellows for providing entrance of a cooling fluid and electrically connecting said switch member to said second contacts and permitting movement of said switch member in predetermined directions.

2. A switch for high-frequency currents comprising a plurality of fixed first contacts, a movable switch member being provided with a plurality of second contacts each of which may be alternately connected to one of said fixed first contacts, said switch member comprising two arms each having a rigid top part, a bellows having a thickness of between .005 and .008 of an inch, a hollow tube part flattened at the lower end, and said second contacts secured on each side of the flattened portion of the hollow tube part.

3. A switch for high-frequency currents as set forth in claim 2 wherein said hollow conductive bellows is traversed by a coolant liquid.

4. A switch for high-frequency currents as set forth in claim 2 further comprising a hollow tube for each of said fixed first contacts, said hollow tube being traversed by a coolant liquid.

5. A switch as set forth in claim 2 wherein two fixed first contacts are arranged for conducting high frequency energy to a first operating position, and two second contacts for connecting said second contacts to said fixed first contacts, and two additional fixed contacts for conducting high frequency energy to a second operating position and two additional second contacts for connecting said additional second contacts to said additional fixed contacts.

6. A switch for high-frequency currents comprising a plurality of fixed copper contacts, a movable switch member being provided with a plurality of laminated contacts composed of beryllium-copper plates, each of said laminated contacts being alternately connected to one of said fixed contacts, and said switch member including a hollow conductive bellows for providing entrance of a cooling fluid and a hollow tube having a flattened end portion electrically connecting said switch member to said laminated contacts, said laminated contacts being secured on the flattened end portion of said hollow tube.

7. A switch as set forth in claim 6 wherein contact is made between each fixed contact associated with an operating position and a corresponding laminated contact on said movable switch member, and a toggle mechanism for moving said switch member.

8. A switch as set forth in claim 6 wherein the plates of said laminated contacts are at an angle other than a right angle with the contact surface of the associated fixed contact in the operating position of the movable switch member such that the contact surface of said fixed contact is adapted to be scraped by the laminations as contact between the fixed and laminated contacts is made.

9. A switch as set forth in claim 6 further comprising two toggle mechanisms for moving said switch member, a pair of solenoids, and screening means whereby each toggle mechanism is controlled by a solenoid screened electrically from the high frequency part of said switch.

10. A switch as claimed in claim 6 further comprising a metal frame, two solenoids secured one at each side of the upper part of said frame, a pair of armature members, a toggle mechanism associated with each solenoid and secured to and insulated from said armature members, and four fixed contacts arranged two at each side of the lower part of the frame secured to and insulated from the frame.

References Cited in the file of this patent UNITED STATES PATENTS 721,410 Wood Feb. 24, 1903 757,439 Conrad Apr. 19, 1904 1,039,011 Beck Sept. 17, 1912 1,156,502 Seede Oct. 12, 1915 1,286,001 Hoesohen Nov. 26, 1918 1,316,305 Hoeschen Sept. 16, 1919 1,635,581 Meadowcroft July 12, 1927 1,928,629 Northrup Oct. 3, 1933 1,967,752 Greene July 24, 1934 2,033,743 Shoemaker Mar. 10, 1936 FOREIGN PATENTS 277,338 Italy Sept. 5, 1930 

